Automatic door openers are used to a large extent in i.a. shopping centres and public buildings to facilitate and speed up passage through an entrance or exit provided with a door. This is especially useful for elderly or handicapped persons.
Today, automatic opening and closing of a door is typically controlled by microwave Doppler or active and passive infrared sensors, which detect the motion of a person approaching the door. These sensors merely detect a movement and will not be able to distinguish between different objects approaching the door.
There may be a need for a more intelligent controller of the automatic opening and closing of doors. In US Patent Application Publication No. 2001/0030689, there is disclosed a video image device controlling the opening and closing of a door. Here, a person approaching the door is detected by comparing images of a field of view in front of the door. By using a video image device, the movement of a person could be distinguished from the movement of e.g. a piece of paper blowing in the wind. Thus, the door will not be opened upon detection of any movement, but may be opened only when a person actually approaches the door.
When a more intelligent controller of a door is used, the door will not be opened or held open unless necessary. However, this increases the risk of a person being injured by incorrect opening or closing of the door. Thus, there is a need for an improved handling of detections in an intelligent controller of automatic opening and closing of a door.